1. Field of the Invention
This invention relates to the art of rotary fluid displacement devices such as power steering pumps for automotive vehicles wherein flow control is accomplished with a small servo valve controlling a pressure loaded cheek plate and particularly deals with the coring of integral or cast housings for such devices to accommodate the flow control mechanism.
2. Description of the Prior Art
Heretofore known pumps with integral flow control valves required valve structure to bypass the full pump outlet to inlet and located the valve structure either exteriorly of the pump or as a package incorporated in passages in the pump housing or as a part of various components in a pumping cartridge. In all of these arrangements, flow through the valve at high flow rates produced high Bernoulli reaction forces that had to be offset by heavy springs so that the ports could be closed. These heavy springs increased flow orifice pressure drop, caused heat rise, and frequently required heat sinks or coolers to maintain the fluid at a safe temperature level.